This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This cross-sectional, case control pilot is to determine if there is an association between serum and tissue concentrations of selenium and the diagnosis of thyroid cancer and if so, if the association is gender specific. 200 men and women age 18-80 from all racial groups will be recruited from the endocrinology, internal medicine, and head and neck divisions/department of GUMC (100 already diagnosed with thyroid cancer;100 who do not have thyroid cancer will be controls). There will also be 50 thyroid cancer tissue samples and 50 control goiter or nodular disease tissue samples collected from the GU Tissue Repository.